Stepper motor "standby"

Hello! I'm building a focusing system for my telescope using an Arduino board. Arduino is the interface between the computer (I'm writing a program in C# that is the ASCOM driver for my device), a small board with some buttons (move in, move out and change speed) and LEDs (power on, focusing, 3 LEDs to indicate the current speed), an EasyDriver board and a stepper motor (NEMA-17 - it's a 2 phase, rated 0.33A at 12V, with a resolution of 1.8 degrees - by the way, I set the EasyDriver pot around half-way: is it correct?) that works in microstepping mode.

Everything works fine except the serial comm (I'm not able to increase speed above 9600 baud - I'll look into it at a later stage of my project). The driver can move the stepper a certain number of steps, to a specific position, in and out (by holding a button on the screen) and if I reach the limits (configurable by the driver, managed by the Arduino board) the motor stops. The driver sends a status request every 0.5s to find out if the motor is moving in/out or if it's stopped/sleeping and the position of the motor.

This is my first project with stepper motor, and I really like how they work! I have a couple of questions though, as I don't want to burn down either the motor or the EasyDriver.

(1) I normally turn off the EasyDriver input after the movement is completed (enable pin to high). The result is that the motor's shaft is free to move. The good thing is that in this mode there is no power consumption, but at the same time this could be somehow a problem as ideally if the shaft is locked in position the focuser wouldn't move under the weight of the equipment connected. Is it a problem if I always leave the enable pin to low (for the duration of the astrophotography session - on average about 5 hours straight)?

(2) The stepper and the EasyDriver main IC warm up while operating. The main IC in particular becomes pretty hot. Could this generate problems over time? Is it enough if I attach to the chip a small heat sink or if I cool down the whole box with the boards with a small fan?

Thanks for the help!

  1. Yes this will happen. Try turning the motor drive down to them minimum you need to make it work correctly.

  2. Yes a heat sink will help. Note if you turn the motor drive current down it won’t get as hot.